I think the most effective way of developing the flexibility for the squat is getting under the bar and forcing it into position as much as you can and hold that for a while, 30s at least. You need some weight on the bar to make this work. Do that several times every day for a while and you should see much improvement.
For tight pecs, to me the best stretch is to hold one of those stretchy bands over your head between both straight arms, stretch it apart slightly, and then rotate your arms behind your back and let the band pull your arms together.